This invention relates generally to conveyor mechanism for advancing workpieces in alignment along a predetermined path. The invention is more particularly concerned with can body side seaming, and for purpose of illustration is accordingly specifically directed to coaxially feeding the can bodies in succession, the body feeding means being designed to insure that the joint openings of successive side seams travel a predetermined path coincident with molten effluent of a solder applicator.
In the prior art U.S. Pat. Nos. 3,000,338 and 3,056,368 issued in my name may be noted as representative of a number of side seam soldering machines employed in the can making industry. Such soldering machines and known body makers commonly produce the can bodies at rates of approximately 500/minute. Each body passes over a forming horn, and thence is guided by a stub horn, in end-to-end relation, to a solder applicator, and may thereafter travel to a lap depressor chain. Prior to the arrangement disclosed in my above-cited application, no system is known to have provided positive guidance for maintaining the bodies, especially their side seam joints, in accurate alignment with the applicator. Lack of this alignment feature is an important factor in preventing reduction in can body spoilage. Looked at from another standpoint, provision of means to prevent can body rotation so that each side seam joint is uniformly and properly exposed to molten solder assures that the soldered joints will all be of suitable strength and the solder will be economically applied exactly as required.
When it is desired or necessary to apply inside side striping to can body joints before the heat and solder for side seaming are applied, it is not possible to predeterminedly guide the bodies by internal engagement with the seam joints since this would remove or damage the striping. Therefore the technique disclosed in the above-cited application would not be feasible.
A further distinguishing aspect of this invention is to be noted. So-called drag chains or gripper chains have previously been incorporated in side seam soldering machines. Such device chains have employed non-articulated links, for instance a tapered pin in non-pivotal relation to each chain link, for gripping can ends and advancing them. This prior art design deforms (usually radially enlarges) the trailing can ends for can end mounting but coincidentally also adversely produces the possibility of small cracks or fissures emanating at the can ends from the flaring when the bodies are subsequently flanged. The present invention aims to avoid the propagation of such cracks and inhibit can body rotation during motivation.